(a) Field of the Invention
This invention relates to lower-alkyl 3-acyl-octahydro-2,5-methanobenzo[g]quinoline-3-carboxylates, useful as intermediates for the preparation of 11(eq)-(2-acylethyl)-hexahydro-2,6-methano-3-benzazocines, which in turn are useful as analgesics and narcotic antagonists.
(B) Description of the Prior Art
Sterling Drug Inc.-owned Japanese Patent Appln. No. 60111/75, filed May 20, 1975, published Dec. 26, 1975, under Provisional Patent Publication No. 160275 describes certain 3-acyl-1,2,3,4,4a,5,10,10a-octahydro-2,5-methanobenzo[g]quinolines useful as intermediates for the preparation of 11(eq)-(2-acylethyl)-1,2,3,4,5,6-hexahydro-2,6-methano-3-benzazocines. Even under the most favorable reaction conditions, however, the prior method produces, as a side product, substantial quantities of 2-substituted-1,2,3,4,4a,5,10,10a-octahydro-3,5-ethenobenzo[g]quinolines, thus appreciably diminishing the yield of the desired product, the hexahydro-2,6-methano-3-benzazocines. Essentially identical disclosure to that in the above-indicated Japanese application is found in Michne U.S. Pat. No. 3,932,422, patented Jan. 13, 1976 on an application filed May 20, 1974.